In general, as conventional ashless detergent-dispersants, there have been used a succinimide-based detergent-dispersant, a hydroxybenzylamine-based detergent-dispersant, and the like. With their remarkable actions of dispersing fine particles being highly valued, the ashless detergent-dispersants are extensively used as lubricant additives for a gasoline engine oil, a diesel engine oil, a two-cycle engine oil, and the like. Further, those detergent-dispersants are each regarded as one of very important additives for lubricants, because the detergent-dispersants also have synergistic effects with zinc dialkyl dithiophosphate or a metal-type detergent-dispersant. However, it has often been pointed out that the stability at high temperature and the detergency at high temperature are insufficient.
In general, the conventional ashless detergent-dispersants including a succinimide-based detergent-dispersant and a hydroxybenzylamine-based detergent-dispersant have been insufficient in detergency and stability at high temperature.
Examples of the application of a heterocyclic compound to a lubricant are described in the following patent documents.
In Patent Document 1, there is used benzotriazole as a corrosion inhibitor. Patent Document 2 describes an application of a triazole derivative to a refrigerator oil composition and makes a point in the effect of abrasion resistance. In Patent Document 3, there is used an imidazole fluorine derivative as a surface treating agent. Patent Document 4 describes that polybenzoimidazole is used as a polymer containing an internal lubricant. In Patent Document 5, there is a description on a fluid composition for active suspension containing thiadiazole or benzotriazole and having excellent abrasion resistance. Patent Document 6 describes that a triazine derivative is used as a dispersant for lubricants and fuels. In Patent Document 7, there is a description on indazole thione additives for lubricants. In Patent Document 8, there is a description on a fluid having low traction property which has a triazine structure. Still further, in Patent Document 9, there is a description on a lubricant composition including a triazine derivative.
However, any of the above Patent documents neither describes each of their products as an ashless detergent-dispersant, nor does it particularly make a point in a detergency of their products.    Patent Document 1: JP 01-29497 A    Patent Document 2: JP 06-100881 A    Patent Document 3: JP 06-157471 A    Patent Document 4: JP 07-506860 A    Patent Document 5: JP 08-165483 A    Patent Document 6: JP 2002-534436 A    Patent Document 7: JP 2003-505577 A    Patent Document 8: JP 2004-315703 A    Patent Document 9: JP 2004-331950 A